The mechanism by which the plasmid ColEl is stably maintained and its genes are expressed will be studied. Mutants of ColEl effecting its replication, incompatability and conjugational mobilizability will be isolated. These mutants will be mapped by both endonuclease cleavage pattern analysis and heteroduplex analysis of DNA. The functional analysis of fragments will be examined by generating chimeric and partially diploid plasmids. DNA sequence analysis will be performed on appropriate mutants. Mutants effecting colicin synthesis will also be sought and characterized. The cloning of the DNA of Plasmodium falciparum will also be performed and cells producing antigenically active proteins selected.